1. Field of the Invention
Methods and apparatuses consistent with the exemplary embodiments relate to an impedance matching circuit, and more particularly, to a bonding wire impedance matching circuit which matches impedance in a case where bonding wire is connected with another circuit.
2. Background Art
In millimeter bands, since wavelengths are very short, severe transmission loss may occur even by a small mismatched condition. Especially, bonding wire used between various chips such as transceivers etc. cause severe transmission loss. This is transmission loss due to an impedance mismatch caused by an inductance component of bonding wire which is relatively big in proportion to the wavelength of millimeter frequency broadband, which must be compensated by an impedance matching method to prevent performance degradation.
In a case of an existing millimeter band matching method, most of the designing were made using LC transmission lines. However, embodying such methods require very thin transmission lines of several to dozens of μm, which is difficult to embody in an actual passive environment.
The conventional matching methods using general LC transmission lines is the most widely used method in impedance compensation circuits regarding bonding wire. However, if the bonding wire becomes longer to hundreds of μm, the impedance (Lp) required in the actual impedance compensation circuit becomes greater, which means that very thin transmission lines of several to dozens of μm must be used. This means makes embodying transmission lines very difficult, considering the line width limitations (50 μm) in an actual LTCC process.
In order to compensate this problem, researches have been conducted to design impedance of antennas to match the impedance of bonding wire. However, a problem with this method is that it is difficult to apply to cases where the circuits behind chips are transmission lines and not antennas.
More specifically, researches have been made for methods of compensating chip compensation circuits with input impedance of passive devices such as antennas. This is a method of compensating the inductance of bonding-wire through the input impedance of antennas when designing the antennas, and since it can minimize the matching circuit and thereby minimize the RF system, this method is widely applied to integrations between antennas and chips. However, a problem with this method is that it is difficult to apply to cases where, on circuits behind chips, chips or other transmission lines are arranged instead of antennas.
As such, conventional impedance matching methods have problems. Accordingly, there is a need to seek a bonding wire impedance matching method applicable to various millimeter bands.